1. Field of the Invention
This invention relates to a coupling or attachment device that is useful in orthodontic treatment. More particularly, the present invention concerns an attachment device for connecting an interarch appliance such as a Class II correction appliance to appliances secured to the patient's dental arches.
2. Description of the Related Art
Orthodontic treatment involves movement of malpositioned teeth to orthodontically correct positions. During treatment, tiny orthodontic appliances known as brackets are often connected to anterior, cuspid and bicuspid teeth, and an archwire is placed in a slot of each bracket. The archwire forms a track to guide movement of the brackets and the associated teeth to desired positions for correct occlusion. Typically, the ends of the archwire are held by appliances known as buccal tubes that are secured to the patient's molar teeth. The system of brackets, archwires and buccal tubes are commonly referred to as "braces".
The orthodontic treatment of some patients include correction of the alignment of the upper dental arch with the lower dental arch. For example, certain patients have a condition referred to as a Class II malocclusion where the lower dental arch is located an excessive distance in a rearwardly direction relative to the location of the upper dental arch when the jaws are closed. Other patients may have an opposite condition referred to as a Class III malocclusion wherein the lower dental arch is located in a forwardly direction of its desired location relative to the position of the upper dental arch when the jaws are closed.
Orthodontic treatment of Class II and Class III malocclusions are commonly corrected by movement of the upper dental arch as a single unit relative to movement of the lower dental arch as a single unit. To this end, forces are often applied to each dental arch as a unit by applying force to the brackets or buccal tubes, the archwires, or attachments connected to the brackets, buccal tubes, or archwires. In this manner, a Class II or Class III malocclusion can be corrected at the same time that the archwires and the brackets are used to move individual teeth to desired positions relative to each other.
Correction of Class II and Class III malocclusions is sometimes carried out by use of a force-applying system known as headgear that includes strapping which extends around the rear of the patient's head. The strapping is often connected by tension springs that, in turn, are connected to the buccal tubes, the brackets or one of the archwires. Additionally, as an alternative for correction of Class III malocclusions, the strapping may be connected by tension springs to a chin cup that externally engages the patient's chin. In either instance, the strapping and springs serve to apply a rearwardly-directed force to the associated jaw.
However, headgear is often considered unsatisfactory because it is visibly apparent. Headgear may serve as a source of embarrassment, particularly among adolescent patients who may experience teasing from classmates. The embarrassment can be somewhat reduced if the orthodontist instructs the patient to wear the headgear only at night, but unfortunately such practice may lengthen treatment time since the desired corrective forces are applied during only a portion of each calendar day.
Consequently, many practitioners and patients favor the use of intra-oral devices for correcting Class II and Class III malocclusions. Such devices are often located near the cuspid, bicuspid and molar teeth and away from the patient's anterior teeth. As a result, intra-oral devices for correcting Class II and Class III malocclusions are hidden in substantial part once installed and eliminate much of the patient embarrassment that is often associated with headgear.
Orthodontic force modules made of an elastomeric material have been used in the past to treat Class II and Class III malocclusions by connecting a pair of such force modules between the dental arches on opposite sides of the oral cavity. Elastomeric force modules are often used in tension to pull the jaws together in a direction along reference lines that extend between the points of attachment of each force module. Such force modules may be an O-ring or a chain-type module made of a number of integrally connected O-rings. However, these modules are typically removable by the patient for replacement when necessary, since the module may break or the elastomeric material may degrade during use to such an extent that the amount of tension exerted is not sufficient.
Unfortunately, orthodontic devices such as headgear and removable force modules are not entirely satisfactory for use with some patients, because the effectiveness of the devices is dependent upon the patient's cooperation. Neglect of the patient to faithfully wear the headgear each day or install new elastomeric force modules as appropriate can seriously retard the progress of treatment and defeat timely achievement of the goals of an otherwise well-planned treatment program, resulting in an additional expenditure of time for both the patient and the orthodontist.
As a consequence, a number of intra-oral devices that are non-removable by the patient have been proposed in the past to overcome the problems of patient cooperation associated with headgear and with removable intra-oral force modules. For example, U.S. Pat. Nos. 4,708,646, 5,352,116, 5,435,721 and 5,651,672 describe intra-oral devices with flexible members that are connected to upper and lower dental arches of a patient. The length of the members is selected such that the member is curved in an arc when the patient's jaws are closed. The members have an inherent bias that tends to urge the members toward a normally straight orientation to provide a force that pushes one dental arch forwardly or rearwardly relative to the other dental arch when the jaws are closed.
Other orthodontic devices for correcting Class II and Class III malocclusions are described in U.S. Pat. Nos. 3,798,773, 4,462,800 and 4,551,095. The devices described in these references include telescoping tube assemblies that urge the dental arches toward positions of improved alignment. The assemblies are securely coupled to other orthodontic appliances such as brackets or buccal tubes by the practitioner, and the problems of patient non-compliance are avoided.
Another type of telescoping tube assembly for repositioning the dental arches is described in U.S. Pat. No. 5,711,667. In this patent, a spring is provided to urge a plunger in a direction away from a cylinder to achieve desired movements of the patient's teeth. The spring is described in this reference as being located within the cylinder or external of the cylinder in either coaxial relation or offset, parallel relation to the central axis of the plunger.
U.S. Pat. No. 5,562,445 describes another intra-oral device for moving the position of one dental arch relative to the other. The device disclosed in U.S. Pat. No. 5,562,445 includes first and second telescoping cylinders and a plunger received in the first cylinder. A spring in the first cylinder urges the plunger and the first cylinder in directions away from each other, while the first cylinder and the second cylinder are freely slidable relative to each other.
In the past, it has been common practice to connect the lower end of many of the non-removable intra-oral devices mentioned above to the archwire on the lower dental arch in a space between a pair of adjacent brackets. For example, the devices described in U.S. Pat. Nos. 4,708,646, 5,352,116, 5,435,721 and 5,651,672 have an opening near the lower end of the appliance that is used to receive the mandibular archwire. Similarly, the upper end of the appliance also has an opening that may be used to receive a pin having an enlarged head and a stem that is received in a passage of a buccal tube or other appliance fixed to one of the patient's upper molar teeth.
Preferably, the lower end of the appliances described in U.S. Pat. Nos. 4,708,646, 5,352,116, 5,435,721 and 5,651,672 slides freely in a distal direction along adjacent portions of the mandibular archwire as the patient's jaws are opened and closed. If, for example, such sliding movement is hindered, repeated opening and closing of the patient's jaws may fatigue the appliances, the associated pins or the mandibular archwire to such a degree that breakage may occur. In many instances, the orthodontist will remove brackets affixed to the patient's bicuspid teeth in order to increase the distance that the lower end of the appliances can slide along adjacent portions of the lower archwire.
Unfortunately, removal of the bicuspid brackets to increase the range of sliding movement of the correction devices mentioned above can retard treatment in some instances. For example, movement of the bicuspid teeth toward final desired positions for orthodontically correct occlusion is hindered during the time that the bicuspid brackets are not in place. The bicuspid brackets can be rebonded to the bicuspid teeth in order to help move the latter once the Class II correction appliances are removed, but such a procedure is somewhat time consuming and may extend the overall length of treatment time.
Occasionally, orthodontists have attempted to avoid the problems noted above by connecting the lower end portion of Class II correction appliances to an auxiliary wire that extends along the lower archwire. In some instances, the auxiliary wires are soldered by the orthodontist on both ends to the lower archwire, and a ball stop is provided to engage the mesial side of the lower end portion of the appliance. However, such a practice is often considered unsatisfactory because the auxiliary wire must be soldered in place before the archwire is placed in the brackets, resulting in additional work for the orthodontist. Furthermore, the soldered joint may break apart in use and interrupt the progress of treatment, and also necessitate a return visit by the patient to the orthodontist.
In other past instances, an auxiliary wire has been fashioned by the orthodontist with a hook on one end for coupling to an archwire. The other end of such wires has either a hook for coupling to the archwire or a straight section for insertion into a buccal tube. However, it is somewhat time consuming for the orthodontist to cut and shape such an auxiliary wire, and the results are often not entirely satisfactory.
An improved attachment device for intra-oral orthodontic appliances is described in U.S. Pat. No. 5,718,576 and includes an elongated wire that extends for a majority of its length along the archwire in side-by-side relation. That device also includes a crimpable connector fixed to the wire and having wall portions that are deformable in directions toward a passageway of the connector for non-rotatable connection to the archwire.
The attachment device described in U.S. Pat. No. 5,718,576 is advantageous because it enables the lower end of an interarch appliance such as a Class II correction appliance to travel freely a significant distance whenever the patient's jaws are opened without imposing undue stress on the appliance, on the lower archwire or on adjacent brackets. Moreover, none of the brackets normally need be removed for installation or use of the device or appliance. The crimpable connector securely fixes the device to the archwire in an easy manner without the need for soldering and also prevents the attachment device from rotating about the longitudinal axis of the lower archwire, which otherwise might cause the appliance to catch or bind against another appliance in the oral cavity.
While the device described in U.S. Pat. No. 5,718,576 represents a significant advance in the art, there is a continuing need to improve the performance of orthodontic devices and appliances in order to enhance treatment results and increase patient satisfaction. For example, it is important for orthodontic appliances and devices to function in a reliable manner for extended periods of time between appointments. If one of the appliances or devices fails during the course of treatment, the progress of treatment is often interrupted until such time as the patient returns to the orthodontist for repair or replacement of the malfunctioning part. As can be appreciated, such a malfunction represents a time-consuming nuisance for both the practitioner and the patient, and may result in additional expense.
Moreover, it would be desirable to increase patient comfort during the course of orthodontic treatment. Orthodontic appliances are widely regarded as uncomfortable and any reduction in the level of patient discomfort that is achieved would be considered an improvement over existing appliances.